Method of plasticizing urea-formaldehyde condensation products



- Patented Nov; 1-932 mesm- N T ED 'STATES PATENT OFFICE L'E ONARD SMIDTH, OF NEW YORK, N. Y., AND RAY H. CRIS T, OF GBANTWOOD, NEW JERSEY, ASSIGNORS TO LUCO PRODUCTS CORPORATION, OF BROOKLYN, NEW YORK, A

' conrorwrron or DELAWARE METHOD OF PLASTICIZING UREA-FORMALDEHYDE CONDENSATION PRODUCTS One method of forming a urea-formaldehyde condensation product is to react urea and formaldehyde in a water solution-and sults is allowed to gelatinize in molds, after which it is removed to an oven for drying and ageing. In the drying and consequent shrinkin that is a necessary part of the process a ove described there is first formed a hard surface on the material and the subsequent drying and ageing of the material causes shrinkage within the hard outer surface shell, thereby developing strains in the material which cause the material, when of considerable thickness, to crack and disintegrate during the drying and ageing process. When o f:small thickness the material goes through the entire drying and ageing process without cracking but will subsequently crack and disintegrate when cut or broken into smaller parts. Furthermore, in this drying and ageing process the condensation product tends totwist and warp out of shape in the mold because of the internal strains set up in the mold due to the unequal drying of the material.

Our invention consists in plasticizing thematerial after it has been dried and aged, so

that the strains may be removed from the material and the material may be readily shaped, if desired, while in its plastic condition without danger of cracking or disintegration.

We have discovered that the material may be plasticized by subjecting it to a high temperature for a short time, the temperature and the length of time varying according to the character of the material and the thickness of the sheet being treated, especially to the time of drying.

We-have found that in the various materials which we have treated the temperature must be over 100 C. and the period of time should not exceed five minutes.

The material may be heated by various agencies. We have found it preferable to heat it in-a fluid bath such as a mineral oil bath in which the oil is heated to a point Application filed August 22, 1928. Serial No. 801,424.

above 100 C. We have also found that the material should be heated to a point just before cracks begin to appear in material, the proper time being found by experiments with each particular material being treated. As above stated, the-temperature and the time vary according to the character of the material and the thickness of the sheet being treated. I

j Several examples follow'of different. prodnets and the temperature and time required to plasticize the same, so that they would not crack on cutting, and also, so t at they could be properly shaped while in theirplastic condition, without danger of, cracking or disintegrating. I

Example 1.-A material was, prepared in which the mole ratio of urea to formaldehyde was 1.2 to 2. After distillation the material was cast into sheets of'about A in thickness and dried at a temperature of 70 C. At the end of two days a sample of the above material was immersed in mineral oil at a temperature of 150 C. and in forty seconds it became sufiiciently plastic to be shaped as desiredwithout danger of cracking or disintegrating. At the end of four days another sample of the material was immersed in'minerali' oilgjat a vtemperature of 165 G. and it became 'sulfieiently -pl astic in forty seconds; =Atithe' endof eight days still another sample ofthe same material "was immersed in mineral oil at a temperature of sixty seconds.

180 C. and it became sufiiciently plastic Example 2.Another material was prepared in which the mole ratio of urea-formaldehyde was 1 to 2. 1 Thiswas dried several months in the oven. A sample of this material was immersed in mineral oil at a temperature of 165 C. and it became sufliciently plastic in sixty seconds. This sample was later fractured and placed in an oven but did not crack or disintegrate. Another sample of this same material which had not been plasticized was placed at the same time in the same oven and it did fracture and disintegrate.

From the above description it will be seen that urea-formaldehyde condensation prod- 2 a --1.886,ooo

nets of various characteristics may te plas ticized and thus made capable of being shaped, if desired, without dangerbfcrackin or disintegration, at we claim is:-

1. Plasticizing a previously castsolid urea; formaldehvde condensation product, after it has been dried and aged for removing'the strains from the material, by subjecting it to a high temperature for a short time.

2. Plasticizing a previously castisolid ureaformaldehyde condensation product, after it has been dried and aged for removing .the strains from the material, by subjecting it boa high temperature for a short time and shaping the product while in its plastic conditlon. v A

3. Plasticizing a reviously cast solid ureaformaldeh de con ensation product, after it has been ried and a ed for removingthe strains from the material, by subjecting it to 3 temperature above. 100 C. for a short 4. Plasticizinga reviously cast solid ureaformaldeh de con ensation product, after it has been ried and aged for removing the strains from the material, by subjecting it to a high temperature for a period not e x-' ceedin five minutes.

5. P asticizing a reviously castsolid ureaformaldeh de con ensation product, after it has been ried and aged for removing the strains from the material, by subjecting it to a temperature above 100 C. for a period not exceeding five minutes.

In testimony, that we claim the foregoing as our joint invention,'we have signed our names'this twentieth day of August, 1928.

LEONARD SMIDTH. RAY' H. 'CRIST. 

